AB1440 ASSESSMENT OF THE PREVALENCE OF SARCOPENIA IN ADULT WITH JUVENILE IDIOPATHIC ARTHRITIS
Authors: I. Slitine, A. Hittinger, I. Charlot-Lambrecht, B. Loïs, M. Geoffroy, J. H. Salmon
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Sarcopenia is a progressive and systemic disorder of skeletal muscles responsible for an acceleration of function impairment and loss of mass muscle [1]. It is well known associated with ageing, but a new life-course approach suggests that muscle mass and function in older people also depends on the mass muscle peak in early adulthood [2]. Prevalence increasement of sarcopenia has been well described in inflammatory rheumatic diseases, particularly in rheumatoid arthritis and spondylarthritis, but has never been studied in rheumatic diseases with a juvenile onset. <h3>Objectives</h3> The aim of this study was therefore to investigate the prevalence of sarcopenia in juvenile idiopathic arthritis in adult life. <h3>Methods</h3> We performed a monocentric cross-sectional study including patients followed up in rheumatology unit of Reims hospital for juvenile idiopathic arthritis (JIA) from November 2021 to September 2022. Each patient received a measurement of muscle quantity and quality by dual-energy X-ray absorptiometry, a measurement of muscle strength by Grip test, a screening for sarcopenia by the SCARC-F score, an assessment of physical activity by the IPAQ score and of fatigue by the FACIT-F score. The diagnosis of sarcopenia was confirmed by a decrease in appendicular muscle mass (AMM) &lt; 20 kg in men and &lt; 15 kg in women or an ASM/height<sup>[2]</sup> &lt; 7 kg/m<sup>2</sup> in men or &lt; 5.5 kg/m<sup>2</sup> in women [1]. <h3>Results</h3> Thirty-four patients were included, aged from 18 to 45 years. The prevalence of sarcopenia was 20.6% (7/34) with a majority of women (sex ratio 0.6). Type of JIA was significantly different between the 2 groups with 57.14% oligoarticular form and 28.57% systemic form in the sarcopenic group, versus 44.4% oligoarticular form and 29.6% enthesitic form in the non-sarcopenic group (p=0.043). We did not find any significant difference in disease activity nor in treatment by biotherapy or corticosteroids between the 2 groups. Proportion of patients with a BMI &lt;18.5 kg/m² was significantly higher in the sarcopenic population (p=0.0095). The IPAQ score showed a lower energy expenditure in the sarcopenic group, although not significantly different (p=0.099). By using a variation of -2DS of appendicular skeletal mass or &lt;ASM/height<sup>[2]</sup> compared with age- and sex-matched reference values from a Danish cohort, we have calculated a prevalence of sarcopenia of 11.76% in our population [3]. The assessment of muscle strength defined by a -2DS decrease in grip test values compared to reference values matched for age and sex showed a decrease in muscle strength in 29.4%. By using European Working Group for Sarcopenia in Older People (EWGSOP) definition, only 11.76% of our patients presented a muscle strength decrease. Moreover, the SARC-F score established in patients over 65 years of age did not allow for the detection of sarcopenia in our population. <h3>Conclusion</h3> This is the first study to evaluate sarcopenia in juvenile idiopathic arthritis. JIA is associated with a risk of developing sarcopenia at an early age with an impact on peak muscle mass and, thus, on long-term muscle function prognosis. In order to prevent this risk, nutritional management and regular physical activity seem to be relevant approaches. The definition of sarcopenia by the EWGSOP does not seem to be adapted to a younger population, with a low sensitivity screening of sarcopenia in this population by the SARC-F score and an underestimation of low muscle strength by the grip test. Further studies with a larger population and a control population are needed to clarify these results. <h3>References</h3> [1] Cruz-Jentoft AJ, Bahat G, Bauer J, Boirie Y, Bruyère O, Cederholm T, et al. Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing. 1 janv 2019;48(1):16- 31. [2] Sayer AA, Syddall H, Martin H, Patel H, Baylis D, Cooper C. The developmental origins of sarcopenia. J Nutr Health Aging. 2008;12(7):427- 32. [3] Suetta C, Haddock B, Alcazar J, Noerst T, Hansen OM, Ludvig H, et al. The Copenhagen Sarcopenia Study: lean mass, strength, power, and physical function in a Danish cohort aged 20-93 years. J Cachexia Sarcopenia Muscle. déc 2019;10(6):1316- 29. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.